OpenGL programs

1. Extract the zip file glut-3.7.6-bin.zip to obtain the following files

glut32.lib

glut.h

glut32.dll

2. Copy the above files to the following directories

c:\program files\microsoft visual studio\vc++\lib\glut32.lib

c:\program files\microsoft visual studio\vc++\\include\GL\glut.h

c:\program files\microsoft visual studio\vc++\\windows\system\glut32.dll [ in NT machines at ..\winnt\system32\ ]

3. Steps to follow while opening a new project.

1. Fire up Visual Studio

2. Create a new project as Win32 Console application.
File -> New -> Project -> Win32 Console Application -> An Empty Application

3. Create a new c++ file.(write the code)

4. project à settingsà use MFC as a shared dll

5. Ready to build . Go F5 ...

List of Programs

1. A simple Introductory OpenGL program
2. An OpenGL program to display a cube.
3. A program to explain double buffering concept.
4. A program to perform smooth shading.
5. A planet program to demonstrate translation and rotation.

1. A simple introductory program on OpenGL

Expected output:

Source code:

#include 

#include 

void display(void)

{

/* clear all pixels  */

   glClear (GL_COLOR_BUFFER_BIT);

/* draw white polygon (rectangle) with corners at

 * (0.25, 0.25, 0.0) and (0.75, 0.75, 0.0)  

 */

   glColor3f (1.0, 1.0, 1.0);

   glBegin(GL_POLYGON);

      glVertex3f (0.25, 0.25, 0.0);

      glVertex3f (0.75, 0.25, 0.0);

      glVertex3f (0.75, 0.75, 0.0);

      glVertex3f (0.25, 0.75, 0.0);

   glEnd();

/* don't wait!  

 * start processing buffered OpenGL routines 

 */

   glFlush ();

}

void init (void) 

{

/* select clearing color       */

   glClearColor (0.0, 0.0, 0.0, 0.0);

/* initialize viewing values  */

   glMatrixMode(GL_PROJECTION);

   glLoadIdentity();

   glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);

}

/* 

 * Declare initial window size, position, and display mode

 * (single buffer and RGBA).  Open window with "hello"

 * in its title bar.  Call initialization routines.

 * Register callback function to display graphics.

 * Enter main loop and process events.

 */

int main(int argc, char** argv)

{

   glutInit(&argc, argv);

   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);

   glutInitWindowSize (250, 250); 

   glutInitWindowPosition (100, 100);

   glutCreateWindow ("hello");

   init ();

   glutDisplayFunc(display); 

   glutMainLoop();

   return 0;   /* ANSI C requires main to return int. */

}

2. An OpenGL program to display a cube

Expected output:

Source code:

#include 

#include 

void init(void) 

{

   glClearColor (0.0, 0.0, 0.0, 0.0);

   glShadeModel (GL_FLAT);

}

void display(void)

{

   glClear (GL_COLOR_BUFFER_BIT);

   glColor3f (1.0, 1.0, 1.0);

   glLoadIdentity ();             /* clear the matrix */

           /* viewing transformation  */

   gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

   glScalef (1.0, 2.0, 1.0);      /* modeling transformation */ 

   glutWireCube (1.0);

   glFlush ();

}

void reshape (int w, int h)

{

   glViewport (0, 0, (GLsizei) w, (GLsizei) h); 

   glMatrixMode (GL_PROJECTION);

   glLoadIdentity ();

   glFrustum (-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);

   glMatrixMode (GL_MODELVIEW);

}

void keyboard(unsigned char key, int x, int y)

{

   switch (key) {

      case 27:

         exit(0);

         break;

   }

}

int main(int argc, char** argv)

{

   glutInit(&argc, argv);

   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);

   glutInitWindowSize (500, 500); 

   glutInitWindowPosition (100, 100);

   glutCreateWindow (argv[0]);

   init ();

   glutDisplayFunc(display); 

   glutReshapeFunc(reshape);

   glutKeyboardFunc(keyboard);

   glutMainLoop();

   return 0;

}

3. A program on Double Buffering concept

Expected output:

This is a simple double buffered program. Pressing the left mouse button rotates the rectangle. Pressing the middle mouse button stops the rotation.

Source code:

#include 

#include 

static GLfloat spin = 0.0;

void display(void)

{

   glClear(GL_COLOR_BUFFER_BIT);

   glPushMatrix();

   glRotatef(spin, 0.0, 0.0, 1.0);

   glColor3f(1.0, 1.0, 1.0);

   glRectf(-25.0, -25.0, 25.0, 25.0);

   glPopMatrix();

   glutSwapBuffers();

}

void spinDisplay(void)

{

   spin = spin + 2.0;

   if (spin > 360.0)

      spin = spin - 360.0;

   glutPostRedisplay();

}

void init(void) 

{

   glClearColor (0.0, 0.0, 0.0, 0.0);

   glShadeModel (GL_FLAT);

}

void reshape(int w, int h)

{

   glViewport (0, 0, (GLsizei) w, (GLsizei) h);

   glMatrixMode(GL_PROJECTION);

   glLoadIdentity();

   glOrtho(-50.0, 50.0, -50.0, 50.0, -1.0, 1.0);

   glMatrixMode(GL_MODELVIEW);

   glLoadIdentity();

}

void mouse(int button, int state, int x, int y) 

{

   switch (button) {

      case GLUT_LEFT_BUTTON:

         if (state == GLUT_DOWN)

            glutIdleFunc(spinDisplay);

         break;

      case GLUT_MIDDLE_BUTTON:

      case GLUT_RIGHT_BUTTON:

         if (state == GLUT_DOWN)

            glutIdleFunc(NULL);

         break;

      default:

         break;

   }

}

/* 

 *  Request double buffer display mode.

 *  Register mouse input callback functions

 */

int main(int argc, char** argv)

{

   glutInit(&argc, argv);

   glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);

   glutInitWindowSize (250, 250); 

   glutInitWindowPosition (100, 100);

   glutCreateWindow (argv[0]);

   init ();

   glutDisplayFunc(display); 

   glutReshapeFunc(reshape); 

   glutMouseFunc(mouse);

   glutMainLoop();

   return 0;   /* ANSI C requires main to return int. */

}

4. A program to perform smooth shading.

Expected output:

Source code:

#include 

#include 

void init(void) 

{

   glClearColor (0.0, 0.0, 0.0, 0.0);

   glShadeModel (GL_SMOOTH);

}

void triangle(void)

{

   glBegin (GL_TRIANGLES);

   glColor3f (1.0, 0.0, 0.0);

   glVertex2f (5.0, 5.0);

   glColor3f (0.0, 1.0, 0.0);

   glVertex2f (25.0, 5.0);

   glColor3f (0.0, 0.0, 1.0);

   glVertex2f (5.0, 25.0);

   glEnd();

}

void display(void)

{

   glClear (GL_COLOR_BUFFER_BIT);

   triangle ();

   glFlush ();

}

void reshape (int w, int h)

{

   glViewport (0, 0, (GLsizei) w, (GLsizei) h);

   glMatrixMode (GL_PROJECTION);

   glLoadIdentity ();

   if (w <= h)

      gluOrtho2D (0.0, 30.0, 0.0, 30.0 * (GLfloat) h/(GLfloat) w);

   else

      gluOrtho2D (0.0, 30.0 * (GLfloat) w/(GLfloat) h, 0.0, 30.0);

   glMatrixMode(GL_MODELVIEW);

}

void keyboard(unsigned char key, int x, int y)

{

   switch (key) {

      case 27:

         exit(0);

         break;

   }

}

int main(int argc, char** argv)

{

   glutInit(&argc, argv);

   glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);

   glutInitWindowSize (500, 500); 

   glutInitWindowPosition (100, 100);

   glutCreateWindow (argv[0]);

   init ();

   glutDisplayFunc(display); 

   glutReshapeFunc(reshape);

   glutKeyboardFunc (keyboard);

   glutMainLoop();

   return 0;

}

5. A planet program to demonstrate translation and rotation.

Expected output:

Interaction: pressing the d and y keys (day and year) alters the rotation of the planet around the sun.

Source code:

#include 

#include 

static int year = 0, day = 0;

void init(void) 

{

   glClearColor (0.0, 0.0, 0.0, 0.0);

   glShadeModel (GL_FLAT);

}

void display(void)

{

   glClear (GL_COLOR_BUFFER_BIT);

   glColor3f (1.0, 1.0, 1.0);

   glPushMatrix();

   glutWireSphere(1.0, 20, 16);   /* draw sun */

   glRotatef ((GLfloat) year, 0.0, 1.0, 0.0);

   glTranslatef (2.0, 0.0, 0.0);

   glRotatef ((GLfloat) day, 0.0, 1.0, 0.0);

   glutWireSphere(0.2, 10, 8);    /* draw smaller planet */

   glPopMatrix();

   glutSwapBuffers();

}

void reshape (int w, int h)

{

   glViewport (0, 0, (GLsizei) w, (GLsizei) h); 

   glMatrixMode (GL_PROJECTION);

   glLoadIdentity ();

   gluPerspective(60.0, (GLfloat) w/(GLfloat) h, 1.0, 20.0);

   glMatrixMode(GL_MODELVIEW);

   glLoadIdentity();

   gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

}

void keyboard (unsigned char key, int x, int y)

{

   switch (key) {

      case 'd':

         day = (day + 10) % 360;

         glutPostRedisplay();

         break;

      case 'D':

         day = (day - 10) % 360;

         glutPostRedisplay();

         break;

      case 'y':

         year = (year + 5) % 360;

         glutPostRedisplay();

         break;

      case 'Y':

         year = (year - 5) % 360;

         glutPostRedisplay();

         break;

      case 27:

         exit(0);

         break;

      default:

         break;

   }

}

int main(int argc, char** argv)

{

   glutInit(&argc, argv);

   glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);

   glutInitWindowSize (500, 500); 

   glutInitWindowPosition (100, 100);

   glutCreateWindow (argv[0]);

   init ();

   glutDisplayFunc(display); 

   glutReshapeFunc(reshape);

   glutKeyboardFunc(keyboard);

   glutMainLoop();

   return 0;

}